Modern communication networks may carry data using optical signals transported across optical fibers. One technique for carrying communication data on an optical fiber is wavelength division multiplexing (WDM). WDM is a technique that allows multiple optical signals to be carried on a single optical fiber. In WDM, optical signals may be separated according to wavelength, where each wavelength may carry a channel of data. For example, WDM may encode ten channels of data onto a single optical fiber by encoding each data channel onto one of ten different wavelengths.
WDM signals may be dropped from a fiber and/or added to a fiber using devices such as re-configurable optical add/drop multiplexers (ROADMs). A ROADM is a device that allows one-or-more wavelengths to be removed from, added to, or remain untouched on a WDM fiber. As a result, a ROADM may be used to “drop” an optical signal from the fiber, such as might occur when an optical signal is made available to a user device. A ROADM may also be used to “add” a signal to a WDM fiber, such as might occur when an optical signal is placed onto a WDM fiber by a user device. An untouched optical signal may pass through a ROADM without being manipulated by the ROADM.
ROADMs may employ optical tuners to drop and/or add optical signals to a WDM fiber. Optical tuners may operate by allowing an optical signal with a particular wavelength to pass through the tuner while reflecting other wavelengths in the WDM data stream. Optical tuners may disturb wavelengths other than the particular wavelength being added and/or dropped. When other wavelengths are impacted, the wavelengths are referred to as being “hit”. Minimizing and/or eliminating hits may help WDM networks operate more reliably.